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The orthodontic management of congenitally missing maxillary lateral incisors and second premolars is the subject of this case report. The primary orthodontic consideration was the maintenance of facial esthetics in a 12-year-old boy while consolidating, aligning, and coordinating the dental arches. The maxillary canines were orthodontically positioned in the lateral incisor spaces. The maxillary posterior teeth, including the deciduous second molars, were protracted to esthetic positions where they could function without interferences. The stability of the occlusion depends on the longevity of the maxillary deciduous second molar roots, which did not resorb during active tooth movement.

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Cephalometric radiographs of a tissue equivalent plastic encased dry skull, each made with eight different screen/film combinations, were compared for usefulness in making orthodontic analyses. The eight screen/film combinations chosen ranged in relative speed from 80 to 600. Only one grid cassette was used, and it was a Par speed screen/film combination. Ten orthodontists identified 13 selected anatomic landmarks and rated the adequacy of their radiographic images. The density of each cephalometric radiograph was analyzed for each anatomic landmark. The results showed a difference in density readings for the various landmarks visualized. The optical density preferences of the 13 anatomic landmarks ranged between 0.87 and 2.09. The study leads to the conclusion that cephalometric radiographs can be taken with screen/film combinations that provide maximum useful information with a minimum dose level to the patient.

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A multidisciplinary approach to the management of teeth traditionally classified as nonrestorable is presented. Three case histories are described in which such teeth are extruded orthodontically, the gingiva and biologic width are repositioned apically, and the teeth are restored.

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To provide an improved data base for predicting the soft-tissue changes that accompany mandibular advancement surgery, short- and long-term serial cephalograms from the records of eighteen patients were analyzed. Hard- and soft-tissue landmarks were located on serial tracings and later were reduced to rectangular X-Y coordinates for computer-generated measurement data and statistical analyses. The interpretation of mean value, ratio, and regression equation data showed that the lower lip, inferior labial sulcus, and chin tissues moved forward and downward. The mandibular short-term (mean = 3.7 months postsurgery) horizontal change means were greater than the long-term (mean = 18 months postsurgery) horizontal change means. The posteriorly directed long-term means may result from functional adaptations that follow the short-term surgery-related spatial changes. These data also show the need for long-term prediction data to supplement the short-term data base.

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Uprighting of molars is indicated as an adjunct to restorative and periodontal procedures. Limiting conditions exist in which previously reported helical and box-loop springs cannot be used effectively. In those instances, segmental arch wires with T-loops upright the molars efficiently while maintaining control in three planes of space. Furthermore, these loop designs permit immediate engagement of these appliances. Clinical experiences with these springs by students in the professional and graduate dental clinics at the University of Kentucky College of Dentistry lead to the conclusion that: segmental uprighting arch wires with T-loops are easy to fabricate and use; T-looped uprighting springs can be engaged immediately and used efficiently in instances in which helical spring or box-loop uprighting appliances are contraindicated; T-looped uprighting springs offer excellent controlled movements of teeth in three planes of space; acceptance by the patient is favorable; and treatment time, depending on the amount of tooth movement required, is rapid and varies between 8 to 16 weeks.

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Intrauterine thyroidectomies were performed on nine lambs on or about the ninety-sixth postconception day. Seven other control and shamoperated lambs, and the cretin lambs were sacrificed immediately after birth. The mandibles were removed and sectioned at the midline. The right side molars were removed by dissection and caliper measured. The distal cusps of the third primary molars were sectioned, dehydrated, and embedded in Bioplastic. A slow speed diamond saw was used to section the plastic blocks and the embedded teeth. Subsequent grinding and polishing produced high quality 75 micrometer sections of the lamb molar cusps. No significant differences in tooth size or enamel thickness existed. Microscopic examinations show that parts of the cretin enamel were poorly calcified, an observation that was correlated to the intrauterine thyroidectomies. The data suggest that hypothyroidism alters ameloblastic activity during the secretory phase of enamel formation.

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A vertical analysis involving ten linear measurements was developed to localize skeletal and dentoalveolar dysplasias. The measurements are of biologic relevance, reflecting the amount of growth harmony or disharmony to the examination and record-taking time. The vertical dimensional analysis uses the age- and sex-related University of Michigan mean values for comparative data for each measurement. Ratios were computed for a five-unit proportional analysis. Both analyses were applied to assess the vertical problems of three female patients. The analyses detected specific areas of dysplasia for each patient.

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The forensic dentist can estimate the age of an individual by observing the developing dentition. Systematic observations can provide accurate age estimations depending of the criteria used and the experience and training of the dentist. Anatomical, histological, and radiographic examinations of the teeth are of great value. Admittedly, some of the aforementioned methods are complicated and require prolonged time periods to perform. Alternative methods of age estimation may be required when rapid results are demanded by the police or other agencies. It is, however, the obligation of the forensic dentist to provide the precise age data. Therefore, all available resource materials must carefully evaluated, including the possible factors that may cause variations. Only after data is carefully evaluated can the error in age estimations be reduced.

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Quantitative data permit the variability comparison of crown-root ratios computed from periapical films of a single central incisor taken by five technicians using the bisection-of-angle and the paralleling long-cone techniques. The paralleling long-cone technique produces significantly less distortion and is less variable. It is the method of choice for assessing natural root resorption and resorption due to orthodontic therapy.

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The data given on the cusp size of maxillary first permanent and second primary molars support the following conclusions. The qualitative literature on cusp size hierarchy requires revision because the quantitative data suggest that the mesiolingual cusp is largest, the distobuccal cusp second largest, the mesiobuccal cusp third largest, and the distolingual cusp smallest. Sexual dimorphism is apparent only when reflected as a collective measure of total occlusal area, a summation of cusp and ridge sizes. Antimere variations are random for individual cusps and collective measures of total occlusal areas mask observable right-side, left-side cuspal variations. Similarly, cross-twin and co-twin analyses of cusp size heritability indicate a low level of hereditary variability.

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Overall measures of mandibular molars reflect the combined size contributions of the component cusps and ridges. Until now, the size hierarchy of primary and permanent mandibular molar cusps remained unclear. This paper utilizes the relative plane surface areas (basal area dimensions) of the individual molar cusps, as assays of cusp size to demonstrate cusp size variations within populations, antimere cuspal variations, sexual dimorphism, and, the heritability of cusp size. Duplicate dental casts from 199 pairs of like-sexed twins provide the raw dats. Defined anatomic landmarks on the occlusal surfaces were reduced to X-Y rectangular coordinates prior to the computation of the basal areas dimensions. The results establish a cusp size hierarchy specific for molar type, i.e., five-cusped molars with a distal fovea and distal marginal ridge (5fd), five-cusped molars without a distal fovea and without a distal marginal ridge (5o), and four-cusped molars (4c). Sexual dimorphism in cusp size is apparent in 5fd molar cusped but not in 5o molar cusps. However, males have a significantly higher frequency of 5fd molars. Females have a higher frequency of smaller 5o and 4c molars which have fewer crown components. Moreover, female 5o molars have cusps as large as or larger than 5o male molor cusps. Right-side-left-side differences exist between antimere cusps based on relatively low correlations. The mirroring of molor types occurs infrequently. When observed, most intrapair differences for cusp size, using F-ratios, indicate a low component of hereditary variability.

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